We hypothesize that the mammalian homologue of Fasciclin Il (mamFas II/OCAM), a member of the IgSF CAMs, is responsible for the greater degree of fasciculation and growth of axons from explants derived from ventral and lateral OE where OSNs express mamFas II at a high level, by comparison with dorsal and medial OE where neurons express little or no mamFas II. My project began to address the role of this cell adhesion molecule (CAM) in axonal guidance, in the context of the olfactory system. We will assess the involvement of mamFas II in fasciculation and growth by blocking mamFas II function by bath application of anti-mamFas II antibodies to cultured explants from dorsal vs. ventral OE, and measuring the extent of fasciculation and growth. In addition, the expression of high levels of mamFas II by stably transfected 3T3 cells upon which explants are grown will delineate the guidance properties of this CAM acting in isolation. In this manner, we hope to elucidate the role of mamFas II in developing OSNs. This determination will have implications for other areas of the nervous system that differentially express mamFas II during development, as well as enhance our understanding of the incredible accuracy with which OSNs form synapses throughout life.